Fundamental knowledge concerning the metabolism and function of very long chain fatty acids (VLFA) in man is lacking. Current interest in VLFA metabolism has been heightened by the demonstration that patients with the X-linked inherited disease adrenoleukodystrophy (ALD) accumulate VLFA in various tissues, including cultured fibroblasts. Long-term objectives of the proposed research are to establish the biochemical basis for VLFA accumulation in ALD, determine whether genetic heterogeneity is responsible for phenotypic variability in affected individuals, and uncover the pathogenetic mechanisms resulting in organ dysfunction. Accordingly, we will investigate the rate and control of VLFA synthesis and turnover in normal and ALD fibroblasts using radio-chemical techniques. These methods will be used to clarify the mechanism whereby VLFA accumulation in ALD fibroblasts is decreased by incubation in the presence of oleic acid. The relative contribution of peroxisomal and mitochondrial pathways to total VLFA oxidation will be determined in cultured fibroblasts, adrenocortical cells, hepatocytes, and glioma cells. Individual VLFA Beta-oxidation enzymatic activities will be characterized in rat liver, and these assays will be applied to normal and ALD fibroblasts in an attempt to identify the putative enzymatic defect in ALD. Genetic complementation studies with fibroblasts will be used to investigate possible genetic heterogeneity in ALD, and the ALD gene will be further mapped on the X-chromosome by chromosome-mediated gene transfer techniques. The pathophysiologic basis for adrenal insufficiency in ALD will be investigated in a model system employing adrenocortical cells cultured in the presence of VLFA. These studies will provide fundamental information about normal VLFA metabolism and the deranged VLFA metabolism in ALD.